Speedometer.



A. A. CANTON.

SPEEDOMETER.

APPLICATION FILED JUNE 2], 1914.

1,227,747. Patented May 29, 1917.

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UNITED STATES PATENT OFFICE.

ALLEN A. CANTON, OF NEW YORK, N. Y., ASSIGNOR TO THE DEVICE TESTINGCOMPANY,

A CORPORATION OF CONNECTICUT.

SPEEDOME'IER.

Specification of Letters Patent.

Patented May 29, 1917.

Application filed June 27, 1914. Serial No. 847,669.

To all whom it may concern:

Be it known that I, ALLEN a citizen of the United States of America, anda. resident of the city, county, and State of New York, have inventedcertain new and useful Improvements in Speedometers, of which thefollowing is a specification.

This invention relates to speedometers operated by electricity and theobject of the invention is to provide a speedometer of novel, simple andpractical construction. Other'objects of the invention will appearhereinafter.

Accordingly this invention'comprises such parts and elements arrangedand combined as hereinafter set forth and as illustrated in theaccompanying drawings in which A. CANTON,

Figure 1 is a face view of a speedometer embodying my invention,

Fig. 2' is a side view with the casing in section, and

Fig. 3 is a wiring diagram.

The reference numeral 5 denotes a casing for suitably containing andsupporting the various parts. Fixed to the said casing are twoelectro-magnets 6 and 7 each of which is in the form of a horseshoemagnet wound with the coils 8, 8 and 9, 9 in a direction to producepoles 10, 10 and 11, 11. The two poles of each of the magnets 6 and 7are of similar polarity and spaced a distance apart.

The two magnets 6 and 7 are so wound that the poles 10, 10 0f the magnet7 are of opposite polarity to the poles 11, 11 of the magnet 6 whencurrent is supplied to the coils 8 and 9. The poles 10 and 11 are 13 isan armature of soft iron mounted to move on a spindle 14 pivoted in thecasing and in a bridge piece 15 by means of an arm 16 which is prolongedto form a pointer 17 which moves over a scale 18. 19, 19 are stops forlimiting the movement of the pointer and the armature 13, WhlCh lattermoves within the magnetic field of the poles 10 and 11 of the respectivemagnets as shown in Fig. 2.

Referring to Fig. 3 the coils 8 of the magnet 7 are connected across thebattery 20. A resistance 21 serves to decrease the magnetic strength ofthe coils 8 with respect to the coils 9 so that the two magnets 6 and 7are always at different magnetic strength.

' terruption.

. The coils 9 of the magnet 6 are connected magnetized toothed disk 23secured to the shaft 24, the speed of which is to be measured, and anoscillating armature 25 which is permanently magnetized with a polarityopposite to that of the disk 23. When the shaft 24 is at rest, themagnet 6 is short circuited by way of the interrupter 22 and wires 26,27 and 28 leading from the interrupter to the battery. 29 is aresistance to prevent short circuiting on the battery.

The coils 8 being supplied with a constant electric current energizesthe magnet 7 which attracts the armature l3 and moves it into theposition shown in Fig. 1 where the pointer is at zero.

When-the shaft 24 commences to rotate, the interrupter armature 25 isoscillated, as will be understood, permitting current impulses to passthrough the coils 9 which then energize the magnet 6. The faster theshaft 24 moves, the greater is the frequency of current impulses passingthrough the coils 9 and whereby the magnetic strength of the poles 11 isincreased in proportion to the frequency of the impulses, it beingunderstood that the parts are so timed and arranged that the periods ofimpulses are greater than those of in- Consequently the armature isattracted by the poles 11 and moves on its spindle 14 proportionate tothe frequency of the current impulses. The movement of the armature 13is indicated by the pointer 17 on the scale 18.

I have found this speedometer to work very accurately in actualpractice. The construction of the electromagnets insures that thearmature 13 is completely within the infiuenceof their magnetic fieldand responds instantly to the difference in magnetic strength of the twomagnets 6 and 7.

The invention is susceptible of changes and the detailed constructionmay be varied within the scope of the appended claims without departingfrom the principle of the invention.

I claim 1. A speedometer comprising a pair of electromagnets ofdifferent magnetic strength, means for supplying a constant electriccurrent to the one electromagnet, means for supplying an intermittentelectric current to the other electromagnet to increase its magneticstrength, an armature mounted to move in response to the difference inelectric strength of the said two electromagnets and means forindicating the movement of the said armature.

2. A speedometer comprising a pair of electromagnets of differentmagnetic strength, each of said electromagnets being in the form of ahorseshoe magnet havin poles of equal polarity and spaced a istanceapart, an armature. mounted to move within the magnetic field of the twoelectromagnets and between the poles of each one of the same and inresponse to the difference in magnetic strength of the said twoelectromagnets, means for indicating the movement of the said armature,means for limiting the movement thereof and means for supplying electriccurrent to the two magnets.

3. A speedometer comprising two electromagnets of opposite polarity andof different magnetic strength, each of said magnets being a horseshoemagnet with poles of equal, polarity, an armature mounted to oscillateWithin the magnetic field of the said two electromagnets and between thepoles of each one of them, a pointer secured to said armature, a scalefor said pointer and means for supplying electric current to the saidtwo electromagnets.

Signed at New York, N. Y., this 26th day of June, 1914.

ALLEN A. CANTON.

Witnesses:

WALTER S. MORTON, IVAN KONIGSBERG.

